Recently there have been developed decorative coatings of nickel-iron alloy for application to conductive substrates. The electrodeposition of such alloys and suitable baths for such use are disclosed in U.S. Pat. No. 3,806,429, assigned to the assignee of the present invention and in an article entitled "Decorative Coatings of Nickel-Iron Alloy", published in Plating magazine, August, 1973 edition.
As is disclosed in these references, and as practiced in the prior art, bright leveled alloy deposits can be obtained from nickel-iron plating baths containing complexing agents in combination with certain primary and secondary organic brighteners. The complexing agents are hydroxy carboxylic acids, for example, sodium gluconate, sodium citrate and the like.
In general, the prior art nickel-iron plating baths are capable of consistently producing bright, leveled nickel-iron alloy deposits containing up to about 30 percent iron. Alloy deposits of higher iron content have previously been impractical, since higher concentrations of iron in the bath are necessary and thereby even relatively low concentrations of ferric ions are detrimental. Excess ferric iron in the bath reduces the brightness and leveling properties of the deposit, increases the internal stress of the deposit, and reduces ductibility. The problems of ferric iron formation in the bath are even more acute where air agitation is used.